The present invention relates generally to weight lifting exercise machines, and is particularly concerned with a leg exercise arm for such machines.
Weight lifting machines normally have a leg extension/leg curl arm pivoted at the front end of the machine adjacent the seat and linked to the exercise resistance to permit a user to perform leg exercises. Such devices are described, for example, in U.S. Pat. Nos. 4,678,185 and 4,915,377 of Mahnke. The exercise arm in these machines is straight. In some prior art leg exercise arms, a pulley is mounted on the straight arm, for example the 880-3D Home Gym of Hoist Fitness Systems has a pulley at the end of the straight exercise arm. The problem with straight leg exercise arms is that the exerciser will experience a drop off or reduction in resistance while performing an exercise. This is because the exercise arm goes through an arcing motion, and the cable attached to the arm is therefore not pulled at a constant rate. In order to prevent the drop off in resistance, some manufacturers have attached a cam or curved piece of metal to the end of the exercise arm, providing a surface for the cable to wrap around during the second half of an exercise movement, so that the cable is pulled at an even rate during the entire movement. However, this adds to the expense of the machine and also causes design restrictions due to the rearward protrusion of the cam.
The straight leg exercise arm also has a second disadvantage when a pulley is mounted at the end of the arm for performing other exercises such as upper body, standing position exercises. The user stands facing the machine and pulls the cable upward using various handle attachments. In order to perform such exercises, the exerciser must stand back from the machine to avoid damaging the cable by rubbing it against the front of the machine. This requires additional floor space. It can also be difficult to access the cable attachment point if the pulley is located at the end of the straight arm.
One possible solution to these problems is to mount the pulley on the bottom front of the exercise arm. However, this will cause the cable to rub against, or bend round, the bottom of the exercise arm when in use, unless a cam is attached to prevent this. Another solution is to eliminate the pulley at the lower end of the exercise arm altogether, and to attach the cable permanently to this arm. In this case, another location must be provided on the machine for performing the additional upper body exercises.